1. Field of the Invention
The present invention relates to an injection molding machine, and more particularly, to an injection molding machine with an electric storage device.
2. Description of the Related Art
In general, an injection device and a mold clamping device of an injection molding machine are driven by a servomotor, which is supplied with driving power from its drive unit to advance or retreat a screw and a movable platen for moving the mold clamping device. The injection device is expected to move the screw at high speed, and the mold clamping device is also expected to quickly move the movable platen that supports a mold, so that high electric power is required.
If a large servomotor is driven with high output in this case, high power must be supplied from an amplifier to the servomotor. However, a large-capacity transformer is needed in order to cover all the high power with electric power from a main power supply, so that the costs may be considerably increased. To solve this problem, there is a method in which an electric storage device is previously charged with electricity so that the high power required for high output can be derived from the electricity with which the electric storage device is charged. However, this method requires the electric storage device for high power charging to be installed separately from the injection molding machine.
Conventionally, the electric storage device of this type used to be disposed separately from the injection molding machine. In installing the injection molding machine, therefore, the installation location of the electric storage device must be secured independently of that of the injection molding machine. Since the electric storage device must be moved along with the injection molding machine, moreover, the movement may take time in some cases.
Japanese Patent Application Laid-Open No. 2000-141440 discloses a technique in which an electric storage device for supplying electric power to an injection device is disposed outside the injection molding machine, in a motor drive unit for an injection molding machine.
In either of the above prior art techniques, the electric storage device is disposed separately from the injection molding machine. As described above, therefore, the installation location of the electric storage device must be secured independently of that of the injection molding machine, and the electric storage device must be moved along with the injection molding machine, so that the movement may sometimes be time-consuming.